The methodology sets out a sample testing approach which can be applied to group rooms into those of similar room type or performance requirement category or construction type.
Where rooms are grouped to the same use and construction for instance, only 1 in 4 pairs of adjacent rooms would need to be tested, and the results would be representative of all similar rooms e.g. where there are 12 pairs of similar offices and 3 are tested and are compliant, all 12 would be deemed compliant (or 100%).
Therefore, it is not a requirement to test 80% of the rooms to be 80% compliant for those projects where a sampling approach can be applied.